[enh][mod] engine list updates

searx/settings.yml

     locale : en-us
     shortcut : ddg
 
-  - name : filecrop
-    engine : filecrop
-    categories : files
-    shortcut : fc
+# down - website is under criminal investigation by the UK
+#  - name : filecrop
+#    engine : filecrop
+#    categories : files
+#    shortcut : fc
 
   - name : flickr
     engine : flickr
     shortcut : fl
     timeout: 3.0
 
+  - name : general-file
+    engine : generalfile
+    categories : files
+    shortcut : gf
+
   - name : github
     engine : github
     categories : it